DNA Extraction Home Experiment Kit (£12.49 + P&P)

DNA (short for Deoxyribonucleic acid) is a molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses. Most DNA molecules consist of two strands coiled around each other to form a double helix. DNA in animals, plants, and fungi is located within a membrane called the nucleus of a cell. This itself is protected from the outside environment by a cell membrane, which consists of two layers of phospholipids. Therefore, in order to extract DNA from the strawberry cells, the phospholipid cell walls and nuclear membranes must first be broken (cell lysis).

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How Does This Kit Work?

DNA can be extracted using a detergent-based extraction buffer, which is what you will make in this kit. Just like dishwashing detergent dissolves fats (lipids) to clean plates, the nuclear membrane extraction buffer will dissolve the phospholipids holding the cell together. With the cell wall being disrupted, the contents of the cell are allowed to flow into buffer solution. This is called the lysate or cell extract. The detergent-based extraction buffer also contains salt (NaCl). The salt causes some of the cellular debris in the lysate to precipitate out of solution whilst the DNA remains in solution. The precipitate can then be removed via filtration. The DNA is soluble in the aqueous cellular (water) environment, but is insoluble in alcohol (such as isopropanol). Applying a layer of alcohol on top of the filtrate causes the DNA to precipitate out of solution at the point where the alcohol and the filtrate meet. Once this happens you can physically see the DNA and it can be physically manipulated. Strawberries are an excellent source of DNA, as they are multicellular and octoploid. This means that they have eight copies of their seven chromosomes in each cell compared to us humans who only have 2 copies (diploid). Strawberries also produce pectinase and cellulase enzymes that contribute to the breakdown of cell walls, making DNA extraction relatively easy to accomplish using this kit.

What’s in the box?

Freeze dried strawberries, isopropyl alcohol, detergent, test tube, 2 x filter paper, 2 x zip lock bags, modelling clay, funnel, 2 x wooden sticks, nitrile gloves (medium), 0.05ml scoop, 1 x pipet, and 1 x totally awesome MP button badge.


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The Experiment

  • Empty the freeze-dried strawberry powder into the zip locked bag.
  • Place one scoop of sodium chloride (table salt) using the scoop into the zip locked bag.
  • Add five drops of the detergent in the squeeze drop bottle into the zip locked bag.
  • Fill the plastic tube with water and then pour into the zip locked bag. Do this twice to get the correct amount of water. Be careful to keep the back upright as the contents may spill.
  • Squeeze the zip locked bag with your hands to mush the freeze dried strawberry powder.
  • Place on the side until needed later.

 

  • Get the plastic tube and place the funnel on top of it.
  • The test tube and filter is top heavy and may fall over. To prevent this, use the modelling clay to make a stand by rolling it up into a sausage shape and then put it around the test tubes. Press it against the test tube and the surface. This should keep it in place, but still be careful not to knock it over.
  • Place the filter paper in the funnel.
  • Pour the contents of the zip locked bag into the filter. A red solution should then start to fill the plastic test tube.

 

  • Once finished remove the funnel and filter.
  • Slowly add approximately half of the isopropyl alcohol down the side of the plastic test tube using the pipet so it does not disturb the red solution. The alcohol layer should sit on top of the strawberry extract layer.
  • Leave the solution for 10 minutes.
  • White strands should appear where the two liquids meet.
  • Using the stick, slowly and carefully poke the clumps of DNA in the alcohol layer and rotate. Remove the stick, and the DNA should be attached.

 

You have now successfully extracted DNA! You can try the experiment again with a fruit of your choice. We recommend a banana or kiwi.